Rail arrangement

ABSTRACT

One aspect of the invention provides a rail arrangement in which a rail is releasably supported in an inner shell, and the inner shell and rail are received within an outer shell. This provides flexibility in that the design of the inner shell can be varied to provide different relative positioning of the rail with respect to the outer shell. Thus, the inner shell can be used to take account of sinking of the outer shell, which is typically cast into the rail foundations.

[0001] This invention relates to rail arrangements for a railway ortramway system.

[0002] A conventional rail essentially comprises an I-beam, having ahead, a narrow web and a base. The rails are supported at regularintervals by the sleepers, using clips which bear down upon the widebase of the rail. The rail spans the spacing between sleepers, and theI-beam structure provides the required vertical strength of the railacross these spans.

[0003]FIG. 1 shows an alternative rail design which has been proposed.The rail 20 is held in a shell 22 set in a bed or slab 24 of concrete.The shell 22 has an inner profile of an open channel to receive the rail20 whilst also clamping the rail 20 in place. A resilient filler 26 isprovided between the shell 22 and the rail 20.

[0004] The rail cross section comprises a head portion 20A and asupporting portion 20B. In the example shown in FIG. 1, the top of thesupporting portion 20B has a pinched part 28. To insert the rail 20 intothe shell 22, the wider lower part of the supporting portion 20B has topass through the pinched region of the fill 26, so that the rail musteffectively be sprung into the shell with a snap-action fit.

[0005] Despite this pinched part 28 of the rail cross section, the headportion 20A and the supporting portion 20B have substantially the samewidth. The only differences in width are provided to enable thesnap-action fitting of the rail into the shell as described above, andnot to provide the conventional I-beam cross section.

[0006] The bed or slab 24 is lower on one side of the rail than on theother side, to allow the passage of the flange of a wheel of the railedvehicle. However, the shell 22 provides support for as much as possibleof the height of the rail 20 on both sides of the rail. In particular,the shell 22 provides support for at least part of the head portion 20Aon both sides of the rail, and over the entire height of the supportingportion 20B on both sides. The rail design of FIG. 1 is described ingreater detail in WO 99/63160.

[0007] The shell 22 defines a continuous supporting structure for therail 20, rather than the discontinuous sleeper arrangement of the moreconventional rail system.

[0008] There are a number of issues surrounding the use of asubstantially rectangular section rail. The rail has a lower secondmoment of area (for a given weight of steel per unit length) than anI-beam rail, so that an increased volume of steel is required for thesame structural stiffness. To some extent, this issue is resolvedbecause the rail is supported along its full length. However, it isstill desirable to use material most efficiently.

[0009] Another issue is the settlement of the foundations on which therail is mounted, and the consequent lowering of the rail, which mayrender the surface of the rail uneven. The same issue arises if the railwears outside of the required alignment tolerances. In the system ofFIG. 1, the shell is concreted into the slab and can not therefore bemoved, so that no adjustment of the rail position is possible unless theslab itself is raised or the fill (which is a supporting pad) is changedand the thickness is increased. However, this adjustment is limited.

[0010] A further issue is that the arrangement of FIG. 1 has differentheights on each side of the rail, making the arrangement unsuitable foruse as a tram rail arrangement or for switches and crossings.

[0011] According to a first aspect of the invention, there is provided arail arrangement comprising:

[0012] a rail;

[0013] a resilient layer around at least the base of the rail; and

[0014] an inner shell for receiving the rail and the resilient layer,and having an inner profile corresponding to the outer shape of theresilient layer,

[0015] wherein the inner shell and rail are received within an outershell.

[0016] In this arrangement, the “inner shell” (which is the part whichretains the rail in place) is received in an outer shell. The innershape of the “inner shell” is thus designed to co-operate with the rail,and the outer shape is designed to cooperate with the “outer shell”.This provides flexibility in that the design of the inner shell can bevaried to provide different relative positioning of the rail withrespect to the outer shell. Thus, the inner shell can be used to takeaccount of sinking or heave of the outer shell, which is typically castinto the supporting foundations which may be subject to sinking orheaving (rising).

[0017] A resilient or conforming layer may be provided outside the innershell.

[0018] Preferably, the inner shell and rail are removably receivedwithin the outer shell, so that at least a portion of the inner shellscan be changed in shape to correct for wear or sinkage or heave. Theinner shell may for example be formed from pre-cast concrete or steel.

[0019] The inner shell may be heavier than the resilient layer, and itmay then have sufficient mass to act as a mass damping component. Formass damping, a stiff resilient layer is required between the rail andthe mass damping component, with a further preferably softer) resilientlayer between the mass damping component and the support structure(namely the outer shell). Therefore, for using the inner shell as a massdamping component, a resilient or conforming layer is also providedoutside the inner shell. Thus, the arrangement can combine benefits ofadjustability with mass damping capability.

[0020] The inner shell can be made to enable a non-rectangular rail tobe fitted into a rectangular outer shell. For example, an I-beam railmay be used, and the inner shell can have an inner profile correspondingto the outer shape of the rail and a substantially rectangular outershape. The resilient layer around the rail takes up tolerancedifferences between the rail and the inner shell. The outer shape isdesigned for co-operation with the outer shell, optionally through theadditional resilient layer. The inner shell may have a two-piece crosssection, each piece comprising a lateral portion, so that these piecesmay be assembled around the I-beam rail. This provides a more efficientuse of metal in the rail, but still enables the push fit system to beimplemented. The inner shell may, however, be one-piece or may be formedin more than two pieces.

[0021] According to a second aspect of the invention, there is provideda rail arrangement comprising:

[0022] a rail;

[0023] a resilient layer around at least the base of the rail; and

[0024] a shell for receiving the rail and the resilient layer around therail,

[0025] wherein the rail has a base, a head and a central flange region,and wherein filler portions are provided one each side of the flangeregion, such that the outer shape of the rail and the filler portions issubstantially rectangular, and wherein at least one of the fillerportions comprises a first mouldable material and embedded mass dampingportions of a second material, which is more dense than the firstmaterial.

[0026] A conforming layer is preferably provided between the fillerportions and the rail to allow for tolerance differences.

[0027] This arrangement also enables an I-beam rail to be used withinthe push fit system, and uses the space on each side of the rail flangeto accommodate mass damping components.

[0028] A third aspect of the invention provides an alternative massdamping solution, and provides a rail arrangement comprising:

[0029] a rail;

[0030] a mass damping component beneath the rail and having a widthsubstantially equal to the width of the base of the rail;

[0031] a resilient layer around the rail and the mass damping component;and

[0032] a shell for receiving the rail and the mass damping component.

[0033] Preferably, a resilient member is positioned between the rail andthe mass damping component, for transferring vibrations from the rail tothe mass damping component. This arrangement provides mass dampingwithout increasing the width of the rail assembly. The rail preferablyhas a substantially rectangular cross section.

[0034] According to a fourth aspect of the invention, there is provideda rail arrangement comprising:

[0035] a rail;

[0036] a resilient layer around at least the base of the rail; and

[0037] a shell for receiving the rail,

[0038] wherein the arrangement further comprises a side piece receivedwithin the shell on one side of the rail, the side piece having a firstheight at one side against the rail and a greater second heightcorresponding approximately to the height of the rail at the oppositeside.

[0039] This arrangement enables a rectangular rail cross section to beretained within areas where a flat surface is required. The side piece,which is preferably removable, defines the required flangeway gap forthe wheel flange, and the side piece or the shell define the stop towhich the road surface is prepared.

[0040] The wider shell, for receiving the rail and the side piece, mayinclude the normal shell and a modifying shell portion. Thus, the shellmay comprise first and second outer side walls and an inner side wallbetween the outer side walls, wherein the first outer side wall and theinner side wall define a chamber for the rail (which is the conventionalshell shape) and the second outer side wall and the inner side walldefine a chamber for the side piece (the second outer wall being amodifying piece).

[0041] The side piece can be symmetrical about a centre line dividingthe side piece into a top half and a bottom half, so that it may beturned over when it is worn.

[0042] According to a fifth aspect of the invention, there is provided arail arrangement comprising:

[0043] first and second rails;

[0044] a centre piece received within the shell between the first andsecond rails, the centre piece having a height lower than the height ofthe rails

[0045] a resilient layer around at least the base of the rails; and

[0046] a shell for receiving the rails and centre piece.

[0047] This arrangement enables a dual gauge system to be formed fromtwo rectangular rails in a shared shell, or else enables rails which areconverging together (for example at a crossing) to be mounted in ashared shell.

[0048] According to a sixth aspect of the invention, there is provided arail arrangement comprising:

[0049] a rail;

[0050] a resilient layer around at least the base of the rail; and

[0051] a shell for receiving the rail and the resilient layer around therail,

[0052] wherein the shell has approximately equal height on both sides,and wherein on one side of the rail, the shape of the shell correspondsto the shape of the side of the rail, and on the opposite side of therail, a top portion of the shell has a enlarged width such that a gap isdefined between the top of the rail and the shell.

[0053] This provides an alternative way of providing a flangeway gap,which requires a wider shell with a modified top portion, rather than aseparate insert.

[0054] Examples of the invention will now be described in detail withreference to the accompanying drawings in which:

[0055]FIG. 1 shows a known rail cross section which is an alternative tomore conventional I-beam rails;

[0056]FIG. 2 shows a first rail arrangement of the invention;

[0057]FIG. 3 shows a second rail arrangement of the invention for I-beamrails;

[0058]FIG. 4 shows one way of providing vertical height adjustment;

[0059]FIG. 5 shows one way of provide vertical and lateral adjustment;

[0060]FIG. 6 shows a first modification to FIG. 3

[0061]FIG. 7 shows a second modification to FIG. 3

[0062]FIG. 8 shows a modification to FIG. 2;

[0063]FIG. 9 shows a third rail arrangement of the invention;

[0064]FIG. 10 shows a fourth rail arrangement of the invention forstreet rail systems;

[0065]FIG. 11 shows a fifth rail arrangement of the invention;

[0066]FIG. 12 shows a sixth rail arrangement of the invention providingmass damping;

[0067]FIG. 13 shows a first modification to the arrangement of FIG. 12;

[0068]FIG. 14 shows a second modification to the arrangement of FIG. 12;

[0069]FIG. 15 shows a seventh rail arrangement of the invention;

[0070]FIG. 16 shows a modification to the arrangement of FIG. 15;

[0071]FIG. 17A shows a known arrangement which is a slight variation toFIG. 1;

[0072]FIG. 17B shows a first modification to FIG. 17A to provide astreet system;

[0073]FIG. 18 shows a second modification to FIG. 17A to provide astreet system;

[0074]FIG. 19 shows a third modification to FIG. 17A to provide a dualgauge system;

[0075]FIG. 20 shows a modification to FIG. 17B;

[0076]FIG. 21 shows a modification to FIG. 19;

[0077]FIG. 22 shows an eighth rail arrangement of the invention;

[0078]FIG. 23 shows a first modification to FIG. 22.

[0079]FIG. 24 shows a second modification to FIG. 22.

[0080]FIG. 25 shows a third modification to FIG. 22; and

[0081]FIG. 26 shows a fourth modification to FIG. 22.

[0082]FIG. 2 shows a rail arrangement of the invention. The rail 30 issurrounded by a resilient layer 32, and the rail and layer 32 arereceived as a push fit in an inner shell 34, in a similar way that therail 20 and fill 26 in FIG. 1 are received in the shell 22.

[0083] In the arrangement of the FIG. 2, the inner shell 34 is itselfremovably received in an outer shell 36, with a further resilient layer38 between the inner and outer shells 34,36. This arrangement thusprovides two resilient damping components 32,38. The inner shape of theinner shell 34 is designed to cooperate with the rail, and the outershape is designed to cooperate with the outer shell 36.

[0084] The further resilient layer 38 may be a pre-formed item or it maybe a grout layer applied after the inner shell and rail are in position.This grout may be a poured elastomer or may a concrete based material.The use of a grout enables lateral adjustment of the position of theinner shell relative to the outer shell.

[0085] The outer shell is fixed into the track foundation either bygrouting into a trough or by casting directly into the concrete.

[0086] This design enables the inner shell to provide different relativepositioning of the rail 30 with respect to the outer shell 36 andtherefore the rail foundations. Thus, different shapes of inner shellcan be used to take account of sinking of the foundations, for exampleby providing different designs of inner shell 34 having differentthicknesses at the base part beneath the rail.

[0087] The inner shell is preferably a pre-formed item (moulded,extruded or pulltruded), for example accurately pre-cast concrete, sothat it can define the inner profile for retaining the rail.

[0088] In the example of FIG. 2, the inner shell 34 is relatively thick,and the significant mass of the inner shell can be used for mass dampingthe rail 30 and/or the inner shell can perform a noise damping function.In particular, any vibration of the rail 30 is coupled to the innershell 34 through the layer 32, and the size (particularly the thickness)of the inner shell 34 can be tailored to provide damping of thesevibrations.

[0089] In this case, the material of the layer 32 is selected to beharder than the layer 38 and transfers load to excite the mass dampingcomponent 34. The layer 32 is then a firm resilient material, such as ahard rubber.

[0090] The inner shell also enables a non-rectangular rail to be fittedinto a rectangular outer shell. As shown in FIG. 3, the rail 30 may havean I-beam cross section with a base, a head and a central flange region.The inner shell can have an inner profile corresponding to the outershape of the rail, and a substantially rectangular outer shape. Thisouter shape is designed for cooperation with the outer shell 36. Theinner shell has a two-piece construction so that it may be fitted aroundthe rail 30, each piece comprising a lateral portion. This provides amore efficient use of metal in the rail, but still enables the push fitsystem to be implemented. Again, the inner shell 34 may provide massdamping.

[0091]FIG. 4 shows an arrangement in which there is no resilient layerbetween the inner and outer shells 34,36, and in which the inner shellis a frictional fit inside the outer shell. A wedge piece 31 may beprovided (in addition to friction) to prevent uplift of the inner shell34 relative to the outer shell. FIG. 4 also shows how adjustment of theheight of the rail and the inner shell can be achieved using a baseportion 33 which has a thickness selected in dependence on the requiredlift of the rail. In FIG. 5, a fill 35 is provided laterally outside theinner shell 34 so that the lateral positioning of the inner shell hassome freedom, and when in the correct position, the lateral fill 35, forexample a poured elastomer or poured (or pumped) concrete, can beapplied. The inner shell can again lifted by cutting the fill 35vertically downwards, so that the base portion 33 can be changed to varythe height.

[0092] In the examples of FIGS. 2 and 3, the inner shell is shaped toprovide a detent with the outer shell, so as to prevent uplift of theinner shell in use. It is instead possible to rely upon friction alone.FIG. 6 shows an arrangement based on FIG. 3 in which the inner shell 34has vertical sides. In order to further prevent uplift, securing blocks37 may be provided intermittently along the rail length.

[0093]FIG. 7 shows a modification to FIG. 6, in which the outer shell,instead of being formed as a preformed pad, is formed as a thicker groutlayer 39. This allows lateral alignment of the rail and inner shell 34.The grout layer 39 can then be used for height adjustment instead of theinner shell 34. For example, the grout may applied through tubes runningthrough the inner shell 34, with levelling nuts at the base of thetubes. A levelling bolt is used to raise the rail 30 and inner shell 34(in known manner) and grout can then be pumped to fill the createdspace.

[0094] In the examples above, the inner shell 34 and the outer shell 36(or 39 in FIG. 7) are separated only by a resilient layer. In FIG. 8, athin pre-formed inner shell 34 is used, and an additional precastconcrete block 34A is provided between the inner shell 34 and theresilient layer 38. This means that the components which have hightolerance requirements are all moulded (or extruded or pulltruded)components—the inner shell and the resilient layer 32, The block 34A caneasily be pre-cast or cast around the inner shell as the tolerancerequirements are low. Height adjustment can be carried out by making theouter shell 36 a grout layer as explained with reference to FIG. 7.

[0095] It will be apparent from the various examples above that theinner shell can be held in place with respect to the outer shell byfriction, a wedge arrangement, a mechanical detent, an injected fillwhich acts as a glue, or indeed any combination of these.

[0096] The rail can be retained in the inner shell by friction or by adetent shaping or a combination of these. In addition, the inner shellcan be squeezed against the rail when applying a layer around the innershell (for example the fill 35 in FIG. 5) to increase the frictionalretention of the rail. This may allow the rail to have vertical sides.

[0097] As shown in FIG. 9, the inner shell may be defined by a pouredelastomer 40. In this case, the positioning of the rail 30 relative tothe outer shell is not critical, so that the outer shell may be pre-castinto the concrete foundation. The elastomer fill 40 can then beinstalled in situ, and slight lateral or vertical adjustment of the railposition can be tolerated. Surface treatment of the inner surface of theouter shell 36 can allow the cured elastomer to be removable (with therail) from the outer shell 36. In this example, the elastomer 40 actsboth as the resilient cushion and the inner shell, and may also beprovided with additional mass damping components 42, such as metal rodsrunning along the structure.

[0098] In the example of FIG. 10, the rail is a tramway rail, having aso-called flangeway gap 50 in the rail head. In addition, a separateresilient layer 32 is again provided around the rail. This may betwo-piece (see dotted line at the base) or it may be wrapped around therail. In this example, the rail is grouted into the channel defined bythe outer shell 36, and this grout 52 defines the inner shell. Thegrouting operation again enables the position of the rail in the channeldefined by the outer shell 36 to be less critical so that the outershell can be pre-cast in the rail foundations.

[0099] The grout may be a sand and cement mortar or it may be asphalt ora poured elastomer (as in FIG. 9).

[0100] If the sides of the outer shell 36 in FIGS. 9 and 10 arevertical, the rail may be removable. For example, the inner surface ofthe outer shell 36 can be coated with a de-bonding agent so that therail and elastomer or grout can be removed.

[0101] The example of FIG. 11 has inner and outer shells 34, 36 and thespace between is filled with grout 52 or a poured thermosettingelastomer layer. Again this enables the outer shell 36 to be pre-castinto the bed, but does not allow the simple removal of the inner shell34 (as in the example of FIG. 2). However, initial control of the heightof the rail is achieved when applying the grout (or other materialfiller). For example, the grout may be pumped through a channel asdescribed above. The inner shell can, however, be cut out and removedand re-grouted into an adjusted position. For this purpose, a groutinjection tube may be provided within the structure of the grout layer52 or externally as shown in dotted lines.

[0102] Again, if the sides of the outer shell 36 are vertical, the innershell and layer 52 may be removable. For example, the inner surface ofthe outer shell 36 can be coated with a de-bonding agent so that theinner shell and the grout 52 can be removed. The design needs to ensurethat the inner shell cannot lift in normal use, for example by ensuringsufficient weight and therefore thickness of the grout layer 52 orsufficient friction at the interface between the inner surface of theouter shell and the grout to prevent vertical movement of the grout andshell.

[0103] In the examples above, a heavy inner shell can be used to providemass damping as well as providing the desired adjustability. A furthersolution to providing mass damping is shown in FIG. 12, in which anI-beam rail 30 is received in a shell 60, with a resilient layer 62between the rail and the shell. Filler portions 62 are provided one eachside of the flange region of the rail 30, such that the outer shape ofthe rail and the filler portions is substantially rectangular, to fitinto the outer shell 60 in the same way as the rail system of FIG. 1.

[0104] The filler portions are preformed, for example moulded,components. These may be made from pre-cast concrete, nylon, plastic ora polymer material, as examples. They may be cast, pulltruded, extrudedor formed in other ways, typically less expensively than the formingprocess for the rail steel which they replace. The tight tolerances ofthe engagement mechanism of the rail shape can thus be removed from therail rolling operation and be transferred to the manufacturing operationof the filler portions.

[0105] The advantage of returning to an I-beam rail section is that thegiven weight of rail is more efficiently distributed, which improvesfatigue life (for a given volume of material) or else reduces cost for agiven fatigue strength. The handling weight can be reduced, and thehandling of I-beam rails is more convenient.

[0106] The filler portions can be provided with a number of indentlocations, so that height compensation can be achieved with the samefiller portions, and all that is needed is an additional base support.

[0107] As shown on the left of FIG. 12, at least one of the fillerportions 64 comprises a first low resilience mouldable (or extrudable)material and embedded mass damping portions 65 of a second material,which is more dense than the first material. Portions 65 are typicallymetal inserts.

[0108] The tolerance required in the manufacture of the mass dampingcomponents is also low, as they are surrounded by the low resiliencematerial, which can take up tolerance variations in both the rail andthe mass damping inserts (which will typically be metal or concrete likematerial).

[0109] In the example of FIG. 12, indents 66 are formed in the fillerportions 64, and the overall width provided by the filler portions isthe same as the width of the rail head. In the example of FIG. 13, thefiller portions 64 have flat outer faces, slightly narrower than therail head, so that indent steps are effectively defined at the boundarybetween the filler portions 64 and the head and foot of the rail 30.

[0110] As shown in FIGS. 12 and 13, the mass damping components 65 maycomprise a number of rods (FIG. 12) or a single shaft (FIG. 13) notnecessarily of circular cross section.

[0111] In each case, the rail is coupled to the mass damping elementthrough a resilient, but low resilience, material. This is needed totransfer shock waves from the rail to the mass damping component and toexcite vibration in the mass damping component. In known manner, thisexcitation of the mass damping component can be tuned to damp thevibrations in the rail, which have resulted from mechanical excitationby the train (or tram) wheels.

[0112]FIG. 14 shows how the filler portions 64 may be modified to enablea rail having a wider base than rail head to be accommodated within thesubstantially rectangular shell 60. Essentially, the width of the railwith the filler portions is substantially constant, and must thereforebe brought to the maximum width of the rail by the filler portions ifthe rail is required to be removable. In the case of FIG. 14, themaximum width is the width of the base.

[0113] The filler portions provide mass damping as well as removing thetolerances from the rail manufacture. In the examples of FIGS. 2 and 3,mass damping is provided by a heavy inner shell which surrounds therail, and thereby requires a wider outer shell and increases therequired width of the rail assembly. The examples of FIGS. 12 to 14 donot require increased width, but there is a limited volume of space forthe mass damping inserts.

[0114]FIG. 15 shows an alternative arrangement which provides massdamping without increasing the width of the assembly. A mass dampingcomponent 70 is provided beneath the rail 30 and having the same widthas the rail. The mass of the component is then tuned to provide therequired mass damping. The resilient layer 62 surrounds the rail and themass damping component 70, and a shock transfer member 72 is providedbetween them. This member 72 is a firm resilient material, but of lowresilience. For example, member 72 may be a hard rubber which is softerthan the rail or the damping component 70 but harder than the layer 62.The resilient layer 62 is typically a microcellular polyurethane. Themember 72 transfers vibrations resiliently to the mass damping componentto damp out vibrations in the rail excited by the wheels. Thisintermediate harder layer will adsorb the energy from the rail and warmup. FIG. 16 shows a different thickness component 70.

[0115]FIG. 17A shows a known arrangement similar to FIG. 1. Thedifferences relate to the specific shapes of the components. Thus, therail 30 is received by a shell 22 with a resilient layer 26 betweenthem. The shell has pinch points 23 as shown. Various modifications tothis design provided by the invention will now be described, forproviding a flangeway gap.

[0116] These flangeway gaps are required in main line embedded railtracks, embedded crane or gantry tracks or tram tracks used in thestreet, in level crossings and in switches and crossovers in othertracks.

[0117]FIG. 17B shows an arrangement in which a side piece 80 is receivedwithin the shell 22 on one side of the rail 30. The shell 22 is thuswider than that of FIG. 17A, and this can be achieved using a sideextension 82 to the shell. The side piece 80 is below full height at oneside 84 against the rail and is full height at the opposite side 86.

[0118] One side of the side piece has a shape corresponding to the sideof the rail (the right side in FIG. 17B) so that it provides the detentmechanism with the shell. The inner side of the side piece is shaped toengage the outer surface of the part 22V of the shell.

[0119] The side piece defines the required flangeway gap 88 for atramway rail, and in the example of FIG. 17B, the full height side 86 ofthe side piece 80 defines a stop against which the road surface can beprepared.

[0120] The use of the side extension 82 results in first and secondouter side walls 22A, 22B and the inner side wall 22C between them. Thesame shape of resilient layer 26 can be used, and this has advantagesfor rails which pass between surface mounted regions (for example atswitches and crossings) and normal sections of rail. The rail is thussupported in identical manner throughout, and the transition betweennormal embedded rail support as in FIG. 17A and the surface mountedsupport is facilitated.

[0121] As shown in FIG. 18, the side piece 80 can have symmetrical topand bottom halves, so that it may be turned over when it is worn. Inthis example, the shell 22 does not have a centre section and isdesigned specifically for this use. Note also that the rail itself mayalso be reversible in all examples.

[0122] In FIG. 19, a centre piece 90 is received within the shell 22between first and second rails 30A, 30B, the centre piece having aheight lower than the height of the rails. This arrangement enables adual gauge system to be formed from two substantially rectangular railsin a shared shell. The support of two rails closely side by side is alsorequired in tapered sections of track in switches and crossovers.

[0123] In the examples of FIGS. 18 and 19, the side piece 80 or centrepiece 90 are separate components. Of course, a rail may be formed withthe combined profile, either with one flangeway gap only on the upperface, or with a flangeway gap on upper and lower faces to be reversible.

[0124]FIG. 20 shows a slight modification to FIG. 17B, in which theshell extension 82 is full height and thereby defines the stop againstwhich the road surface is prepared.

[0125] Although the rail in the examples of FIGS. 17 to 20 arerectangular section rails, they may equally be I-beam rails with insertsto make them fit the shell arrangement. These concepts may also beapplied to the twin shell arrangements described for example withreference to FIGS. 2 and 11.

[0126]FIG. 21 shows a slight modification to FIG. 19, in which thecentre piece 90 extends not only between the rails 30A, 30B but alsobeneath the rails. This provides a constant bearing area and ensuresthat the required support resilience is provided without requiringvariations in the compliance of the (elastomeric) resilient layer 26. Inaddition, by providing a low resilience (for example hard rubber) layerbetween the rails and the centre piece 90, it is possible for the centrepiece to provides mass damping, in the manner described above. Thislayer can surround the base of the rails or can line only the bottom andinside face (namely the side in contact with the centre piece 90) ofeach rail.

[0127] These examples provide a flangeway gap, whether for tramwaysystems or between dual gauge rails, by providing an insert alongsidethe rail. The insert may be made of steel, although manufacture fromplastics, composites, polyurethane or rigid elastomer materials may bepossible. Different size flangeway gaps may be desirable for curves andfor straights, requiring different versions of the modified shell andinsert.

[0128] An alternative approach is to modify the shell. In the example ofFIG. 22, the shell 22 has equal height on both sides. On one side of therail (the left in FIG. 22), the shape of the shell corresponds to theshape of the side of the rail. On the opposite side of the rail, a topportion 92 of the shell has an enlarged width such that a gap 94 isdefined between the top of the rail and the shell 22. This gap is therequired flangeway gap. As shown in FIG. 23, a hard insert 96 of steelor polyurethane can line the widened portion of the shell. This insertprotects against damage and wear, for example from contact with thevehicle wheels, and is replaceable.

[0129] In FIGS. 22 and 23 the top portion 92 of the shell is an integralpart of the shell. However, it may be formed as a separate extensionpiece as shown in FIGS. 24 and 25. In FIG. 25, an overlap is provided.Different sizes of separate piece may be used with a standard shell toprovide different flangeway gaps. This extension piece will have outertangs as shown or be formed externally in other ways to enable it toengage with the concrete support.

[0130]FIG. 26 shows another version in which a vertical metal insert 98is provided which acts as a wear plate, and there is a resilient layerand/or shims 99 between the insert 98 and the shell 22.

[0131] These examples all provide flangeway gaps without requiringspecially modified rail shapes.

[0132] In all examples above, the rail has a profile selected to providea detent function with the shell. However, the detent may not berequired, and the engagement of the rail with the shell can be purelyfrictional, particularly if the rail has sufficient mass that it doesnot lift during traffic flow. Intermittent clips additionally may beprovided for holding the rail down.

[0133] Various modifications will be apparent to those skilled in theart.

1. A rail arrangement comprising: a rail; a resilient layer around atleast the base of the rail; and an inner shell for receiving the railand the resilient layer, and having an inner profile corresponding tothe outer shape of the resilient layer, wherein the inner shell and railare received within an outer shell.
 2. A rail arrangement as claimed inclaim 1, wherein the inner shell and rail are removably received withinan outer shell.
 3. A rail arrangement as claimed in claim 1 or 2,wherein the inner shell is formed from pre-cast concrete.
 4. A railarrangement as claimed in any preceding claim, wherein the inner shellis thicker than the resilient layer.
 5. A rail arrangement as claimed inany preceding claim, wherein the rail has base, a head and a centralflange region, and wherein the inner shell has an inner profilecorresponding to the outer shape of the rail and a substantiallyrectangular outer shape.
 6. A rail arrangement as claimed in claim 5,wherein the inner shell has a two-piece cross section, each piececomprising a lateral portion.
 7. A rail arrangement as claimed in anyone of claims 1 to 4, wherein the inner shell provides mass damping ofthe rail.
 8. A rail arrangement as claimed in claim 1 or 2, wherein agrout layer is provided between the inner shell and the outer shell. 9.A rail arrangement comprising: a rail; a resilient layer around at leastthe base of the rail; and a shell for receiving the rail and theresilient layer around the rail, wherein the rail has a base, a head anda central flange region, and wherein filler portions are provided oneeach side of the flange region, such that the outer shape of the railand the filler portions is substantially rectangular, and wherein atleast one of the filler portions comprises a first mouldable materialand embedded mass damping portions of a second material, which is moredense than the first material.
 10. A rail arrangement comprising: arail; a mass damping component beneath the rail and having a widthsubstantially equal to the width of the base of the rail; a resilientlayer around the rail and the mass damping component; and a shell forreceiving the rail and the mass damping component.
 11. A railarrangement as claimed in claim 10, wherein the rail has a substantiallyrectangular cross section.
 12. A rail arrangement as claimed in claim 10or 11, wherein an interface component is provided between the base ofthe rail and the mass damping component.
 13. A rail arrangementcomprising: a rail; a resilient layer around at least the base of therail; and a shell for receiving the rail, wherein the arrangementfurther comprises a side piece received within the shell on one side ofthe rail, the side piece having a first height at one side against therail and a greater second height corresponding to the height of the railat the opposite side.
 14. A rail arrangement as claimed in claim 13,wherein the shell comprises first and second outer side walls and aninner side wall between the outer side walls, wherein the first outerside wall and the inner side wall define a chamber for the rail and thesecond outer side wall and the inner side wall define a chamber for theside piece.
 15. A rail arrangement as claimed in claim 13, wherein theside piece is symmetrical about a centre line dividing the side pieceinto a top half and a bottom half.
 16. A rail arrangement comprising:first and second rails; a centre piece received within the shell betweenthe first and second rails, the centre piece having a height lower thanthe height of the rails a resilient layer around at least the base ofthe rails; and a shell for receiving the rails and centre piece.
 17. Arail arrangement comprising: a rail; a resilient layer around at leastthe base of the rail; and a shell for receiving the rail and theresilient layer around the rail, wherein the shell has approximatelyequal height on both sides, and wherein on one side of the rail, theshape of the shell corresponds to the shape of the side of the rail, andon the opposite side of the rail, a top portion of the shell has aenlarged width such that a gap is defined between the top of the railand the shell.
 18. A rail arrangement as claimed in claim 17, whereinthe top portion of the shell is provided with a lining piece.